Fuzzy matching? - Mailing list pgsql-sql

From Josh Berkus
Subject Fuzzy matching?
Date
Msg-id web-94360@davinci.ethosmedia.com
Whole thread Raw
Responses RE: Fuzzy matching?  ("Robby Slaughter" <webmaster@robbyslaughter.com>)
Re: Fuzzy matching?  (Tom Lane <tgl@sss.pgh.pa.us>)
Re: Fuzzy matching?  (Peter Eisentraut <peter_e@gmx.net>)
List pgsql-sql
Folks,

For many of my programs, it would be extremely useful to have some form
of "fuzzy matching" for VARCHAR fields.  There are two kinds of fuzzy
matching for words that I know of:

1. Phonetic matching, which would be nice but will have to wait for
someone's $100,000 project;

2. Textual mathcing, which I will outline below.

The way textual fuzzy matching should work is as follows:
The developer supplies two VARCHARs to match and a number/percent of
character mis-match that is acceptable:

Fuzzy_match('Thornton','Tornton',1)

And the fuzzy_match should return True if the two phrases are no more
than that number of characters different.  Thus, we should get:

fuzzy_match('Thornton','Tornton',1) = TRUE
fuzzy_match('Thornton','Torntin',1) = FALSE
fuzzy_match('Thornton','Torntin',2) = TRUE

Unfortunately, I cannot think of a way to make this happen in a function
without cycling through all the possible permutations of characters for
both words or doing some character-by-character comparison with
elaborate logic for placement.  Either of these approaches would be very
slow, and completely unsuitable for column comparisons on large tables.

Can anyone suggest some shortcuts here?  Perhaps using pl/perl or
something similar?

Grazie!

-Josh Berkus

______AGLIO DATABASE SOLUTIONS___________________________
                                       Josh Berkus
  Complete information technology      josh@agliodbs.com
   and data management solutions       (415) 565-7293
  for law firms, small businesses        fax 621-2533
    and non-profit organizations.      San Francisco

Attachment

pgsql-sql by date:

Previous
From: Tom Lane
Date:
Subject: Re: union in subselect?
Next
From: "Joe Conway"
Date:
Subject: Re: Fuzzy matching?